The present invention relates to papermaking machines in general, and more particularly to improvements in stock distribution means for delivering an aqueous papermaking slurry of fiber furnish or the like in a papermaking machine. More particularly, the invention relates to improvements in stock distribution means of the type wherein a manifold or an analogous stream dividing device supplies stock (i.e., an aqueous slurry) to a plurality of distributor tubes or conduits which feed stock into a tapering passage having a width equal to or approximating the width of the paper web which is formed in the papermaking machine. In such stock distribution means, the passage serves to deliver stock to the orifice of a nozzle (e.g., a nozzle of the type disclosed in Canadian Pat. No. 614,901 granted Feb. 21, 1961 to David R. Webster) by way of several groups (preferably rows) of channels each having an inlet in communication with the passage and an outlet arranged to direct a jet of stock into the orifice of the nozzle. If the stock distribution means comprises three groups or rows of channels, the inlets of a first row of channels communicate with the passage upstream of the inlets of a second row, and the inlets of such second row communicate with the passage upstream of the inlets of the third row. Furthermore, at least a portion of each channel in the first and third rows converges toward the channels of the second row, and the channels are inclined with respect to the aforementioned distributor conduits which supply stock to the passage.
The quality (especially uniformity) of the web which is formed in a papermaking machine is improved if each group or row of channels receives the same quantity of stock. This can be achieved if the losses of stock flow in the inlets of all channels are the same. German Pat. No. 2,039,293 discloses a stock distribution means wherein losses of stock flow in the inlets of all channels are identical; however, the rate or volume of stock flow in various rows of channels is different because the inclination of channels with respect to the passage differs from row to row. Since the overall losses of liquid flow in a channel include losses at the inlet and losses which are attributable to inclination of the channel with respect to the direction of liquid flow in the passage, losses of liquid flow in the stock distribution means of the type disclosed in the aforementioned German patent vary from row to row. As a rule, such losses are less pronounced in the row of channels whose inlet communicate with the passage upstream of the inlets of the other row or rows of channels because losses due to inclination of channels increase from row to row as considered in the direction of liquid flow in the passage. Therefore, the just discussed stock distribution means is incapable of insuring uniform volume of stock flow in all channels.
German Auslegeschrift No. 2,307,849 discloses another distribution means wherein the inlets of channels are bounded by convex surfaces and the surface bounding the passage opposite the inlets of the channels is curved in such a way that the inclination of each channel with respect to the stream of stock flowing in the passage along the respective convex surface is constant. This insures that the inclination (bend) of all channels is identical. Since the losses at the inlets are also identical or nearly identical, such stock distribution means constitutes an improvement over that which is disclosed in the aforementioned German patent. However, the cost of stock distribution means of the type disclosed in German Auslegeschrift No. 2,307,849 is very high.